You lift the cover, ready to relax, and the topside panel is flashing a short code at you: FLO, OH, dr, Sn. The tub is cold and the jets won’t start. Don’t panic. Most hot tub error codes point to a handful of simple causes, and many of them are fixed by cleaning a filter or topping up the water.
This guide explains the most common codes used by Balboa and Gecko control systems, which power most portable spas sold in the US, including many AquaLife models. Codes vary slightly between control packs, so always check the manual that came with your spa.
First: three checks that fix most errors
Before you look up the code, try these:
- Check the water level. It should sit above the highest jet and the skimmer opening. Low water is the cause of many flow and dry-heater errors.
- Pull out the filter and run the tub without it for a few minutes. If the error clears, the filter is clogged. Clean or replace it. See how to change a hot tub filter, and replacement cartridges like the PRB25-IN filter.
- Open all the jets. Closed jets restrict flow and can trigger errors.
Common hot tub error codes
| Code | What it means | Most likely cause | What to do |
|---|---|---|---|
| FLO, FL1, FLC | Low water flow detected | Dirty filter, low water, closed jets, airlock | Clean filter, top up, open jets, bleed air |
| dr, dry, drY | Heater may be dry | Very low water, airlock after refill, blocked filter | Fill to proper level, clear airlock, clean filter |
| OH, OHH, HH | Overheat: water or heater too hot | Hot summer days, stuck heater, poor flow | Remove cover to cool, check flow; call a pro if it returns |
| Sn, SnA, SnB, SnS | Sensor fault or sensors disagree | Poor flow, loose or failed sensor | Clean filter, restart; persistent codes need a technician |
| ICE, IC | Freeze protection active | Very cold water | Usually normal: the pumps will run to protect pipes |
| Pr, Prr, PRIME | Priming mode after power-up | Normal start sequence | Wait, or press a jet button to exit priming |
| LF, HFL | Repeated low-flow or heater flow problem | Ongoing flow restriction | Find the restriction; call a pro if filter and water are fine |
| — or blank | Temperature unknown | Pump hasn’t run long enough | Run the jets for a couple of minutes |
Fixing flow errors (FLO, dr, LF)
Flow errors are the most common codes by far. The heater needs a steady flow of water across it, and if the sensors detect a weak flow, the system shuts the heater off to protect it.
- Clean the filter with a filter cleaner or a hose. Rotate between two cartridges so you always have a clean one ready.
- Top up the water above the skimmer.
- Bleed an airlock. After you refill a spa, air can get trapped in the pump. With the power off, slightly loosen the pump union until water seeps out, then tighten it. Refilling through the filter housing helps prevent airlocks. Our filling and draining guide shows how.
- Check for debris in the skimmer basket and suction covers.
Fixing overheat errors (OH, OHH)
An overheat code is a safety shutdown. The water may be above 108 to 110°F.
- Don’t get in. Water that hot isn’t safe. Read our hot tub temperature safety guide.
- Remove the cover and let the water cool, adding a little cold water if needed.
- In summer, lower the set temperature and use economy mode, and open the cover for a while in the evening.
- If OH returns on a cool day, the heater relay may be stuck on. That needs a technician. Our hot tub overheating guide covers more causes.
Fixing sensor errors (Sn)
Sensor codes usually mean the two sensors in the heater housing are reading different temperatures. Poor flow is a common cause, so clean the filter and restart the spa at the breaker. If the code comes back within a day, a sensor or the control board may need replacing.
When to call a technician
Call a qualified spa technician if:
- The same code returns after you’ve cleaned the filter, topped up and cleared any airlock.
- The GFCI trips repeatedly. Never keep resetting a GFCI that trips straight away: it’s protecting you from a fault.
- You see water around the equipment bay, or smell burning.
- The tub shows OHH or HH on a cool day.
Keep your model name and serial number ready. For AquaLife spas the warranty and service details are in the owner’s paperwork that came with the tub.
Prevent errors before they happen
- Clean the filter every two to four weeks and replace it every 12 to 18 months.
- Keep the water level correct, especially after heavy use or hot weather.
- Balance the water weekly. Scale from hard water can clog the heater and sensors. Test strips such as these 7-way test strips make it quick.
- Follow a routine like our daily-to-yearly hot tub maintenance guide.
Frequently asked questions
Why does my hot tub say FLO when the filter is clean?
Check the water level, open all the jets and look for an airlock in the pump. If all of those are fine, the flow switch or pressure switch may need adjusting by a technician.
Is the ICE code a problem?
Usually not. It means freeze protection has started. It becomes a problem only if the power goes off. See how to winterize a hot tub.
Can I reset a hot tub error by turning it off and on?
Often yes, by switching off at the breaker for a minute. But if the cause remains, the code will come back.
The bottom line
Most error codes are the tub asking you for clean filters, enough water and good flow. Fix those three first, and keep the manual close by for the rest. If you’re shopping for a new spa instead, compare all AquaLife hot tubs.
